1. Field of the Invention
The present invention relates to a voltage control apparatus of an alternator.
2. Description of the Related Art
Conventionally, in a voltage control apparatus for controlling a voltage generated from an alternator to a predetermined value by turning ON/OFF a voltage applied to an energizing coil of this alternator, the alternator generated voltage is adjusted in a digital manner by employing a microcomputer. Such an alternator voltage control apparatus is typically known from, for example, Japanese Laid-open Patent Application No. Hei 05-176477.
In this type of conventional alternator voltage control apparatus, when the voltage generated from the alternator is controlled to the target voltage under better response characteristic, a target energizing current corresponding to a target current generated from the alternator is calculated by using an equation established based on the power generation characteristic of the alternator. Thereafter, a predicted energizing current, which may actually flow through the energizing coil, is calculated by using an equation established based upon an electromagnetic specification of the alternator.
Then, in response to deviation between the target value of the energizing current and the prediction value thereof, the target energizing current is corrected by way of the primary lead correction based upon both the power generation characteristic and the electromagnetic characteristic of the alternator, and thereafter, the control energizing current is calculated.
Furthermore, an ON/OFF duty ratio with respect to the control energizing current determined by this calculation is read out from a table which is set in accordance with the electromagnetic specification of the alternator. Then, a voltage applied to the energizing coil is controlled based on an ON/OFF duty ratio selected from a map so as to achieve the object, i.e., voltage control.
However, the above-described conventional alternator voltage control apparatus owns the following problems:
That is, in such a case that the power generation characteristic and the electromagnetic specification of the alternator are changed, or in such a case that the presently available power generation characteristic and electromagnetic specification are adapted to other electromagnetic specification and power generation characteristic of alternators, the voltage control apparatus is required to change the ON/OFF duty tables corresponding to the control energizing currents, and the coefficients of the calculating equations for the energizing currents, every time the electromagnetic specification and the power generation characteristic of the alternator are selected. Thus, this alternator voltage control apparatus must again establish the matching conditions.
The present invention has been made to solve the above-explained problems, and therefore has an object to provide an alternator voltage control apparatus in such a case that the alternator is controlled so as to control a generated voltage thereof to a target voltage in a feedback manner, while this alternator voltage control apparatus does not need to employ a parameter and an equation, which are established based upon a power generation characteristic and also an electromagnetic specification of this alternator. That is to say, even when any change is made in the power generation characteristic and also in the electromagnetic specification of the alternator, both the parameter and the equation required in the voltage control apparatus does not need to be changed.
To achieve the above-described object, according to a first aspect of the present invention, a voltage control apparatus of an alternator is characterized by such a voltage control apparatus of an alternator, for controlling a voltage generated by the alternator to a predetermined voltage value by turning ON/OFF a voltage applied to an energizing coil of the alternator, comprising: first logic output means for comparing the voltage generated by the alternator with a target voltage to obtain a magnitude logic which is outputted as a first ON/OFF logic; and second logic output means for outputting as a second ON/OFF logic, a PWM internal output logic in which an ON-duty rate is increased/decreased based on the first ON/OFF logic by an increased/decreased amount defined by considering a time constant of the energizing coil; wherein: a logically processed result between the first ON/OFF logic and the second ON/OFF logic is used as an ON/OFF logic of a voltage application to the energizing coil.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, in such a case that the alternator is controlled so as to control the generated voltage thereof to the target voltage in the feedback manner, this alternator voltage control apparatus does not need to employ the parameter and the equation, which are established based upon the power generation characteristic and also the electromagnetic specification of this alternator. Also, while both the ON-duty rate of the ON/OFF logic of the voltage application to the energizing coil and the logic frequency can be stabilized within a predetermined frequency range, these ON-duty rate and the logic frequency can be set with having compatibility.
According to a second aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that the target voltage is hysteresis-corrected along a direction to hold a magnitude logic obtained by comparing the target voltage with the generated voltage of the alternator; the hysteresis correction amount is changed based on a parameter related to an alternator rotation number and an alternator output strength; and also the hysteresis correction amount is changed in a feedback manner based on an inversion period of the first ON/OFF logic.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the target voltage is hysteresis-corrected in order that the once determined logic is not immediately inverted. Such a hysteresis-correction can be carried out with respect to all possible operation conditions of the alternator.
According to a third aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that the first logic output means is provided with logic inversion suppressing means by which the first ON/OFF logic is hardly inverted; a suppression strength of the logic inversion suppressing means for an ON logic to an OFF logic is made different from a suppression strength of the logic inversion suppressing means for an OFF logic to an ON logic; and the suppression strengths are changed in a feedback manner in response to a resulting logic period of the first ON/OFF logic.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the target voltage is hysteresis-corrected in order that the once determined logic is not immediately inverted. Such a hysteresis-correction can be carried out with respect to all possible operation conditions of the alternator.
According to a fourth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that the logic period of the PWM internal output which constitutes the second ON/OFF logic is changed by executing a calculation based on the parameter related to both the alternator rotation number and the alternator output strength and by retrieving a content of a table; or is changed based on the period of the first ON/OFF logic.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the frequency of the first ON/OFF logic can be firmly set.
According to a fifth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is further comprised of: storage means for storing thereinto a plurality of alternator generated voltages as sampling values, which have been sampled in the past; and calculation means for performing a move average calculation based on the latest sampling value and the plural past sampling values to interpret the move-averaged sampling value as a presently generated voltage; a total referring number of the past sampling values is changed based on the alternator rotation number and the alternator output strength; the total referring number of the past sampling values used in said move average calculation is equal to power of 2; and a total number of referring sampling values is interpreted by a binary number so as to obtain a section average value by bit-shifting only along the right direction by the total referring number.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the section average value can be essentially obtained by employing the software filter, while a complex filter circuit such as a differential filter and an integral filter is no longer required. Also, since the filter strength of this software filter is adjusted under optimum condition based upon the output strength and the rotation number of the alternator, the feedback control operation can be carried out in a higher speed than that of the conventional alternator voltage control apparatus.
According to a sixth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that the generated voltage of the alternator is sampled by a sampling operation whose sampling period is changed.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the effective voltage generated by the alternator can be firmly obtained.
According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the alternator voltage control apparatus is characterized in that the sampling period is calculated based upon the alternator rotation number, or retrieved with the content of the table.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the effective voltage generated by the alternator can be firmly obtained.
According to an eighth aspect of the present invention, in the sixth aspect of the present invention, the alternator voltage control apparatus is characterized in that the sampling operation is commenced by triggering the generation timing of the voltage waveform for one stator phase of the alternator; the sampling operation is intermittently carried out in a predetermined time period only for a predetermined time duration after the commencement of the sampling operation; and both the predetermined time period and the predetermined time duration are calculated based upon the trigger interval up to now, or are determined by retrieving a content of a table.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the density of the sampling process operation is reduced while the program of the microcomputer is executed, so that the computer program can be readily developed. This alternator voltage control apparatus can contribute to the fact that both the microcomputer and the crystal oscillator can be made in low cost since the frequency of the operation clock can be lowered.
According to a ninth aspect of the present invention, in the second aspect of the present invention, the alternator voltage control apparatus is further comprised of: calculation means for calculating the alternator rotation number based upon a time interval of a transition edge from xe2x80x9cLowxe2x80x9d to xe2x80x9cHighxe2x80x9d of a voltage waveform for a stator 1-phase of the alternator.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, since the FV converting operation is carried out, the rotation number of the alternator does not need to be interpreted.
According to a tenth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that the target voltage is shifted by an amount conducted by retrieving a content of a table and by executing a calculation based upon a parameter related to an alternator rotation number and an alternator output strength; or the target voltage is regularly corrected based upon deviation between a voltage appearing at an alternator output terminal, a voltage appearing at an external signal input terminal, and information indicative of a battery voltage derived from an external unit.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the voltage appearing at the battery terminal is not lowered, and the battery voltage can be brought into the stable condition.
According to an eleventh aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that increasing/decreasing of an ON-duty rate of a PWM internal output which constitutes the second ON/OFF logic is suppressed based on an increase/decrease amount per unit time, defined by considering a time constant of the energizing coil; a suppression strength of the increase amount per unit time is set stronger than the time constant of the energizing coil; and further is changed, or prohibited based upon the alternator rotation number; the suppression of the increase/decrease amount per unit time is prohibited, or released based on a specific power generation mode of the alternator; and both an upper limit value and a lower limit value are set to the ON-duty rate based upon the alternate rotation number and the unit temperature.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the hunting operation of the ON-duty rate of the second ON/OFF logic can be eliminated, and a so-called LRC function can be achieved by suppressing the increase of the ON duty rate. Then, since the upper limit value of the ON-duty rate is set, the electromagnetic sound and also the drive torque can be suppressed. Furthermore, since the lower limit value of the ON-duty rate is set, the floating control operation can be carried out.
According to a twelfth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that the ON/OFF logic of the voltage application to the energizing coil is forcibly set to the logic ON based upon either a peak voltage or an average voltage of voltage waveforms for a stator 1-phase of the alternator irrespective of the logically processed result between the first ON/OFF logic and second ON/OFF logic.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, this alternator voltage control apparatus can perform a so-called floating control operation in which even in such a condition that the battery voltage is higher than the target voltage of the alternator and also the alternator does not need to generate the electric power, this alternator generates the electric power to some extent.
According to a thirteenth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that either a multiplied value or an ON-logic rate per unit time of the ON/OFF logic of the voltage application to the energizing coil is interpreted as an ON-duty rate of the voltage application to the energizing coil; and, the multiplied value is obtained from an ON-logic rate within one logic period of the first ON/OFF logic and also an ON-logic rate within one logic period of the second ON/OFF logic.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the ON-duty rate of the voltage application to the energizing coil can be readily recognized.
According to a fourteenth aspect of the present invention, in the thirteenth aspect of the present invention, the alternator voltage control apparatus is further comprised of: calculation means for calculating an effective voltage applied to the energizing coil based upon the ON-duty rate of the voltage application to the energizing coil and a voltage generated from the alternator at this time.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, this alternator voltage control apparatus can contribute to the fact that the precision of predicting the output strength of the alternator and the drive torque thereof is increased.
According to a fifteenth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that both an output strength of the alternator and a drive torque strength of the alternator are predicted by retrieving a content of a table or by performing a calculation, while using an upper/lower width and a voltage magnitude of a voltage ripple produced at an alternator output terminal as a parameter, by retrieving a content of a table or by executing a calculation, while using voltage deviation as a parameter, the voltage deviation between a voltage of an alternator output terminal and a voltage of an external signal input terminal, which are produced by a voltage drop of a recharging line; or by retrieving a content of a table and/or performing a calculation, while using as a parameter, an ON-duty rate of the voltage application to the energizing coil, a converted voltage applied to the energizing coil, and the alternator rotation number.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the digital recognition by the external unit can be easily carried out, and also both the software and the hardware can be readily developed. Further, when the frequency is standardized in the same product, the compatibility on the digital recognition can be established.
According to a sixteenth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is further comprised of: PWM output means for indicating an ON-duty rate of a voltage applied to the energizing coil, an effective voltage applied to the energizing coil, an output strength of the alternator, a drive torque strength of the alternator, or such an ON-duty rate which depends upon a rate of an energizing current itself of the energizing coil and an absolute value of the energizing current.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the digital recognition by the external unit can be easily carried out, and also both the software and the hardware can be readily developed. Further, when the frequency is standardized in the same product, the compatibility on the digital recognition can be established.
According to a seventeenth aspect of the present invention, in the sixteenth aspect of the present invention, the alternator voltage control apparatus is characterized in that the output of the PWM output means contains a predetermined basic frequency; the predetermined basic frequency is changed based upon self-diagnostic information of the voltage control apparatus; even when the basic frequency is changed, the ON-duty rate indicated when the basic frequency is present is not changed; or even when the basic frequency is changed, there is no change in ON time defined by the ON-duty rate indicated when the basic frequency is present.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, since only the frequency of the PWM output and either the ON-duty rate or the ON time are monitored, both the information related to the alternator drive torque and the diagnostic information of the voltage control apparatus can be acquired at the same time.
According to an eighteenth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is further comprised of: an interface used to recognize a voltage related to a battery voltage, and an instruction of the target voltage to an external unit based on a frequency of a pulse signal supplied from the external unit, or both the frequency and a duty.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, the target voltage of the alternator can be changed by the external unit. Also, both the battery voltage and the target voltage can be instructed by the external unit.
According to a nineteenth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that a power supply interrupt of the voltage control apparatus is executed by judging such a fact that the alternator continues an initial energizing condition for a predetermined time period, or such a fact that the alternator continues the initial energizing condition for a predetermined time period and further an alternator rotation number is equal to zero.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, no longer such a trigger means is employed which is dedicated to interrupt the power supply of the voltage control apparatus.
According to a twentieth aspect of the present invention, in the first aspect of the present invention, the alternator voltage control apparatus is characterized in that an initiation of a power supply of the voltage control apparatus is executed by using as a trigger, a logic inversion of an information communication line connected to an external unit.
With employment of the above-described arrangement, the alternator voltage control apparatus owns the following effect. That is, no longer such a trigger means is employed which is dedicated to start up the power supply of the voltage control apparatus.